I'll further add that the landlord being there means they can't simply foist loud, unruly or unsafe temporary residents on an area where he or she does not have any skin in the game. That is, they have to suffer the consequences too. This invariably will lead to less negative externalities.

But this fits into a broader belief that I have, which is that cities should generally be for the residents of them first and foremost before being simply an investment vehicle for a foreign pension fund (for example).

That would mean that in NYC, for example, you get charged much higher property tax if you yourself are not a NYC resident (or possibly NYS resident).